Method and apparatus for controlling weft insertion in looms



Dec. 23, 1969 H. s. STUTZ ET AL METHOD AND APPARATUS FOR CONTROLLING WEFT TNSERTION IN LOOMS 3 Sheets-Sheet 1 Filed March 6, 1967 xon 225m INVENTORS H. S. STUTZ E. LOEPFE any W. M. HRANITZKY +1, 5. STUTZ ET AL METHOD AND APPARATUS FOR CONTROLLING WEFT INSERTION IN LOOMS 3 Sheets-Sheet 2 Filed March 6, 1967 mvmmfifi HSStufz, E. Lee s e. 4 M. M/ /ranfzkg ATTORNEY @ec. 23, 1969 H s, s-ru-rz E'IT AL 3,485,964

METHOD AND APPARATUS FOR CONTROLLING WEFT INSERTION IN LOOMS Filed March 6, 1967 I 3 Sheets-Sheet :5

INVENTORS H, S, Stu'z, E. L 062 2 12 U4 N. MI /ran 25219 BYOLLJLMJA 3-5 41? ATTORNEYS United States Patent 0 US. Cl. 139273 7 Claims ABSTRACT OF THE DISCLOSURE Weft insertion by loom shuttles is controlled by a sensing device producing electric impulses reporting the condition of weft threads, the condition of the shuttle bobbin and, preferably, also the speed of the shuttle, to an evaluating device which may produce electric impulses resulting in the stoppage of the loom or in the replacement of a substantially empty shuttle bobbin by a full one.

This invention relates to a method and apparatus for controlling weft insertion in looms and refers more particularly to a method and apparatus for controlling the weft insertion by loom shuttles wherein a sensing device receives signals from the shuttle and transmits it to an evaluating device for producing operational signals for the loom.

There are three control functions which are particularly necessary for the weft insertion by shuttles, namely,

the control of the supply of thread in the shuttle bobbin, 7

the control of the thread withdrawn from the bobbin as far as breakage or its absence for other reasons is concerned, and the control of the movement of the shuttle.

Methods and devices of this type are known in prior art for each of these requirements. They include a sensing device which usually cooperates with the shuttle without touching it and which produces signals characterizing the condition of a supervisory device in the shuttle or the position of the shuttle. Hereinafter a sensing device will be considered as including all parts cooperating to deliver signals from the shuttle. These signals are treated in the evaluating device, for example, they are compared with previously given data, transformed, delayed and finally used for releasing operational signals for the loom.

For example, US. Patent No. 3,053,139 describes the control of shuttle bobbins by an electro-optical weft feeler having a source of light and a casing containing light-sensitizing means and immovable relatively to the shuttle, as well as a reflecting coating applied upon the stem of the bobbin and constituting the giver of signals for the evaluating device. When the shuttle bobbin is close to becoming empty, the coating which is normally covered by the weft threads is exposed so that it will reflect the feeler light to the light sensitive means. The evaluating device strengthens and extends the duration of this signal impulse and, depending upon the type of the loom, either stops it or starts an automatic bobbin changing device.

A procedure for controlling the weft threads in the shuttle is known, for example, from Swiss Patent No. 396,801. In accordance with this patent, a particularly suitable device is provided by an electro-optical feeler cooperating with a reflector provided in the shuttle, the operation of the reflector being determined by the presence and the condition of the weft thread. If an improper condition is present the sensing will either produce a supervisory impulse or will fail to produce it, with the result 3,485,964 Patented Dec. 23, 1969 ice that the evaluating device will produce an actuating signal stopping the loom.

Swiss Patent No. 389,528 describes a control of the movement of the shuttle, particularly its speed. According to this patent, the feeler device may contain a coil which is immovable relatively to the shuttle and which cooperates with two permanent magnets placed in the shuttle at a specific distance from each other. The process is based on the comparison of the time interval between two signalling impulses produced in the coil as the shuttle flies past it, with a measuring value supplied by a time element of the evaluating device.

In order to provide a complete control of the weft insertion, it is necessary to jointly carry out the dilferent control functions in a loom. However, when separate devices are used, substantial difficulties are encountered in the practice and a large apparatus is required. As far as the feeler is concerned, it is questionable whether it can receive on one side of the loom more than one device, such as an electro-optical sending and receiving device and whether it can be properly adjusted, leaving aside the greater possibility of disturbances and the high costs of providing several of the highly sensitive parts of the control apparatus. On the other hand, each of the control devices must be released separately at suitable times so as to provide the necessary adjustment of the operation to the working cycle of the loom.

An object of the present invention is the provision of a process and apparatus which will make it possible to use a single feeler and evaluating device to carry out simultaneously at least two of the above-described control functions, namely the control of a shuttle bobbin and of the shuttle-carried thread, while control of shuttle speed can be easily added thereto.

Other objects of the present invention will become apparent in the course of the following specification.

The process of the present invention consists primarily in that a sequence of impulses produced by the feeler, which contains at least information about the condition of the weft thread and information about the fullness of the shuttle bobbin, is examined by the evaluating device concerning the reaction of impulses corresponding to this information. Such a sequence of impulses is produced as the shuttle flies periodically past the signal receiving part of the feeler device, whereby information is provided by supplying impulses, or by the absence of impulses, and whereby the impulses can have a specific form, as far as amplitude, modulation, etc. are concerned.

In adition to supervising impulses dependent upon the condition of the shuttle bobbin and of the weft thread, the sequence of signalling impulses should also preferably contain impulses which are produced by marked locations in the shuttle and which serve particularly for supplying information concerning the presence and the speed of the shuttle. Such marking-produced impulses can be also transmitted through a different part of the feeler device.

A particularly advantageous embodiment of the process of the present invention consists in that the release or absence of signalling impulses in a predetermined time interval constitutes information about the controlled conditions. The adjustment of the control to the operation of the loom is then effectively achieved in that the evaluating device investigates whether signalling impulses appear in predetermined phases of the shuttle cycle within predetermined time intervals.

In accordance with the present invention this is preferably carried out with the use of two time systems of diflerent origin, namely, one depending upon the loom and the other defined by the moving shuttle. In each of these time systems, predetermined time intervals are distinguished and the appearance of a signalling impulse during at least one predetermined time interval of the two systems produces the release of a steering signal for the loom. This procedure provides in a particularly simple manner a distinction between the separate phases of the shuttle cycle and the determination of the appearance of predetermined control impulses.

The introduction of a time system combined with the loom, makes it also possible to control the presence of the shuttle and to provide at the same time a certain control for the operativeness of the feeler and evaluating devices in a time interval which is defined independently from them.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings, showing by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGURE 1 is a diagram of an embodiment of a combined control apparatus of the present invention.

FIGURE 2 is a diagram showing the arrangement of signal producing means in a shuttle.

FIGURE 3 is an impulse diagram of the embodiment of FIGS. 4 and 5.

FIGURE 4 is a block switch diagram of an evaluating device for controlling the shuttle bobbin, the warp thread and the presence of the shuttle.

FIGURE 5 is a similar diagram constituting an amplification of that of FIG. 4, showing the simultaneous control of the speed of the shuttle.

FIG. 1 illustrates the connections of the most important parts of a control apparatus located outside the shuttle. The diagram shows two sensing heads TK which are connected to an input of the evaluating device A. A second input of the device A is connected with a generator of timing signals KW, while the outputs of the evaluating device operate actuating devices S and W. The actuating device S serves to stop the loom, while the actuating device W can be provided for looms with automatic bobbin exchange for starting the exchange procedure. Each of the actuating devices S and W comprises a solenoid the plunger core of which is mechanically connected to a corresponding lever on the loom which actuates the stopping or the bobbin change mechanism of the loom. These constructions are well known in prior art and for that reason are illustrated merely diagrammatically herein. The generator KW produces a timing signal preferably from the driving mechanism of the loom, for example, with the aid of a switch actuated by a cam mounted upon the crank shaft; the switch is connected in series with a source of potential so that its closure by the cam at each revolution of the crank shaft will produce a voltage pulse KW at the input of the input of the evaluating device A. The function of this signal in conjunction with the evaluating device will be described in detail later on.

However, the timing signal can be produced by another part of the loom defining the working rhythm of the loom, for example, the batten.

Preferably, signals from the shuttle are derived by electro-optical means. For this purpose the sensing heads TK of the feeler device are constructed in the same manner as that described in U.S. Patent 3,053,139; they cooperate with reflecting elements provided in the shuttle. Preferably the sensing heads are mounted on both sides of the batten; they are scanning the shuttle when it enters the shed and when it leaves the shed. Katadioptric reflectors are particularly suitable as reflecting elements for the purposes of the present invention. By way of example, they may be constructed as control elements in such manner that they are normally covered and are exposed to the sensing light beam in case of a defect. The element signalling the full or empty condition of the weft bobbin consists preferably of a reflective coating applied on the stern of the bobbin where it is covered by the weft thread as long as a sufficient amount of thread is present on the bobbin. When the weft supply is nearly exhausted the reflective coating is uncovered by the unwound thread.

The element signalling the broken or unbroken condition of the weft yarn consists preferably of a pivotally arranged lever which is held in a specific position by the tension of the moving yarn. In this position a reflector carried by the lever is covered inside the shuttle. However. when the yarn breaks, the lever and the reflector swing to a position in which the reflector is uncovered by an opening in the shuttle. Both signalling devices are well known in prior art. Thus when the shuttle flies past the sensing device a defect produces a signalling impulse.

Beside the supervising elements which can be exposed or covered, this embodiment of the present invention provided two other reflectors upon the shuttle which are always exposed and which produce signalling impulses in the light receiver during each passage of the shuttle past the receiver range. These last-mentioned signalling impulses which can be designated as marking impulses. constitute, along with the signalling impulses which characterize a defective condition and which can be designated as control impulses, a sequence of impulses which is examined by the evaluating device with respect to the appearance of impulses during predetermined time intervals.

The marking impulses can be also produced in a different manner, for example, by means of magnets provided in the shuttle and feeler coils fixed upon the batten. A purely optical feeler device is, however, less expensive and is substantially easier to place.

When controlling weft insertion the following four phases of the shuttle cycle, namely the back and forth flight of a shuttle, are of interest:

Phase I.Entry of shuttle into the shed, flight direction i (for example, from left to right).

Phase II.Emersion of shuttle from the shed, flight direction f Phase III.-Entry of shuttle into the shed, flight direction f (for example, from right to left).

Phase I V.-Emersion of shuttle from the shed, flight direction f In this example, the control program should include the control of the presence and intact condition of the weft thread, the control of the weft supply on the shuttle bobbin and the control of the launching of the shuttle, i.e. determination as to whether the shuttle was launched at all. The distribution of these functions among the individual phases of the shuttle cycle may be as follows.

In I: Control of shuttle bobbin.

Control of launching.

In H: Control of weft thread.

In Ill: Control of launching.

In IV: Control of weft thread.

When no launching is reported or when the weft thread is not intact, a control signal is fed by the actuating device S which causes the stopping of the loom, while when the shuttle bobbin is empty, a control signal is fed to the actuating device W which initiates the bobbin exchange.

Instead, in non-automatic looms, the loom can be stopped in the last-mentioned instance as well. For that purpose, it is merely necessary to connect the corresponding outlet of the evaluating device to S.

To carry out this control program, the shuttle is provided with reflecting elements the arrangement of which is schematically shown in FIG. 2. They include control elements LF and SW for the shuttle bobbin and the weft thread, respectively, which have the above-described structure, while M and M are the two marking elements which, as already stated, are always exposed. They consist of pieces of reflective tape fixed on the surface of the shuttle. It is of importance, that the distances between LF and M on the one hand and between SW and M on the other hand should be substantially different from each other and that the two of them should be smaller than one-half the distance M M Hereinafter it will be assumed that the speed of the shuttle after its launching lies within a given range of tolerances. During the scanning of the shuttle pulses issued from the control elements LF and SW can only occur, depending upon the direction of flight of the shuttle, at given points within the time interval defined by the pulses issued from the marking elements M and M The first line (1) of the impulse diagram of FIG. 3 shows the two possible types of the sequence of signalling pulses when the shuttle flies past a feeler head, whereby the control pulses and the marking pulses are designated as LF, SW, M and M corresponding to the signalling elements. The two halves of the diagram correspond to the two fiight directions and f of the shuttle, namely, the phases I, II or II, IV.

The operation of the evaluating device Will be now described on the basis of the block diagram of FIG. 4 and the pulse diagram of FIG. 3. For that purpose the block diagram shows only the functionally important elements; numerals enclosed by brackets represent points at which appear pulses of the correspondingly indicated lines of the pulse diagram.

Signalling pulses appearing at the point (1) at the signal input of the evaluating device, are fed into two parallel lines of transmission gates T T and T T T T which are controlled by time determimng devlces P, R, Z and K. In this example the time determining devices are monostable multivibrators with similarly designated time constants P, R, Z and K; upon arrival of an incoming impulse they provide outgoing impulses of a duration corresponding to their time constant and after the termination of this duration they are again sensitive to the incoming impulses.

The time determining device P is released by an incoming impulse through a differentiating member indicated in FIG. 4 as a condenser, specifically, by the rear edge of the pulse. As shown in the block diagram of FIG. 4, it serves to control the gates T and T the first of which permits the passage of the signalling pulse which reaches its input connected with point (1), provided that at the same time a pulse P arrives at its other input connected with the time determining device, while the second gate T is conductive for a signalling impulse when the time determining device does not supply an impulse P, in other words when the condition P prevails at the output of the time determining device P, which is point (4) in FIG. 4. This manner of indication has been also used for the other logic circuits T -T which are all so-called coincidence gates. In FIG. 4 at each gate the condition is indicated which must exist at the control input of the gate connected with the corresponding time determining device in order to allow transmission of a signalling pulse through the gate (horizontal direction). The time determining device R is released in the same manner as the device P and makes the gate T conductive when an pulse R appears at its output, point (5). The rear edge of the pulse R releases a further time determining device Z which is used to actuate T and T The gate T becomes conductive when condition Z prevails at the output of the time determining device Z, point (6), while the gate T is conductive during the condition Z. The gates T which is in series connection with T and T which is in series connection with T are operated by the time determining device K, whereby T is conductive at K and T is conductive at K. This time determining device K is released by a pulse KM produced by the loom as mentioned in connection with FIG. 1 and appearing at the input (2) of the evaluation device. In the present embodiment of the invention the release of K should take place shortly before the entry of the shuttle into the shed and the time constant of the time determining device K should be so great that the duration of the pulse K is longer than the control interval M M or M M Then the pulse K occurs during the entire control period in the phases I and III, while in the phases II and IV the condition K prevails. Therefore, every time the shuttle passes through the shed the conditions K or K define two time intervals the beginning of which is combined with the operational cycle of the loom.

On the other hand, the time determining devices P, R and Z determine in the described manner time intervals related to the sequence of the signalling pulses and characterized by the conditions P or P, R or R and Z or Z. Thus when a signalling impulse appears, a combination of conditions is present in the evaluating device which is characterized by the simultaneous presence of K or K with P or P, R or R and Z or Z. The evaluation corresponding to a set operational procedure is based upon the fact that a signalling pulse is positively identified by its coincidence with a specific combination of conditions.

For that purpose the values of the time constants are determined in a manner shown in FIG. 3 in relation to the given possible time intervals of signalling impulses. For example, the time determining device Z separates each of the control intervals into two parts corresponding to conditions Z and Z in such manner that in the phases I and II of the shuttle cycle the pulse LF meets the condition Z, while in the phases III and IV it meets the condition Z. Thus the evaluating device, with the assistance of time determining devices Z and K, can distinguish the appearance of an LF control impulse in all four phases, provided that a distinction from other impulses appearing in the same combination of conditions is first left out of consideration. In phase I LF can appear only with K and Z, in phase II with K and Z, in phase III with K and Z and in phase IV with K and Z. Thereafter the time determining devices P and R serve for the final determination of an LP impulse. In principle, they provide a distinction between the impulse distances of M and LF on the one hand and M and SW on the other hand. If a signalling pulse meets an impulse P, it will have from the preceding one a distance characteristic for the appearance of SW. On the other hand, if a signalling impulse meets the conditions P and R jointly, then the previous impulse had appeared at a distance corresponding to the distance between M and LF. From this results directly the combination of conditions adapted to the selected operational scheme of the controlling installation, which must provide passage for a signalling pulse to one of the actuating devices.

(1) If a signalling pulse appears during a time interval wherein conditions K, P, R and Z appear simultaneously, then there is no doubt that the sensing device had provided a control pulse indicating the empty condition of the shuttle bobbin in phase I of the shuttle cycle. Such a signalling pulse (which is here the pulse M appearing in the flight direction f passes, therefore, the chain of gates T T T T and supplies a release pulse m to the actuating device W (see FIG. 3, line (8)).

(2) If a signalling pulse appears in a time interval in which conditions P and K exist simultaneously then a defective condition of the weft thread has been determined in one of the phases II or IV. Such signalling pulse passes the series connection of gates T T and finally supplies 'at (7) a release pulse sw or m for the actuating device S which stops the loom.

As far as the sizes of the time constants are concerned, it should be noted that P and R are so selected that P is somewhat greater than the interval between the impulses M and SW and R is somewhat greater than the interval between LF and M The time constant Z must satisfy the requirement that the time interval R-l-Z released from the first pulse of a control interval, should continue longer than the pulse K, whereby K, as already stated, must be greater than the interval M M The upper limit of Z is here determined by the distance between the two sens- 7 ing heads. However, it can also have another meaning, as will be described hereinafter in connection with FIG. 5.

The control of shuttle launching takes place by an impulse k obtained by differentiation from the rear edge of the pulse K. During normal launching the end of the pulse K is covered by an impulse Z. However, if the pulse k meets at the gate T the condition Z, then this can mean one of two situations. Firstly, it can mean that prior to the arrival of k there was no signalling pulse, at least not up to the point of time which is further back than that corresponding to the length of pulse R, which means that the shuttle was not emitted at all, or was emitted incorrectly. Secondly, it can mean that the control device does not operate either in the sensing section or on the path (1)(5)(6) in the evaluation section. In that case the gate T allows the passage of the pulse k (see FIG. 3, line (7)) and it releases the stop device S. Reversely, the presence of Z at the time of the arrival of pulse k, provides a control for the lauching of the shuttle and also for the functioning of the control device and of the path (1)-T of the signal in the evaluation device.

The supervision of the shuttle regarding its speed can be incorporated in a simple way in the operational program of the described apparatus. By way of example, this supervision may consist in determining whether impulses still appear when the shuttle flies past a sensing bead after the arrival of a first signalling pulse within a predetermined time interval within which no signalling pulses can occur when the shuttle flies with correct speed. The appearance of a pulse within this control interval shows that the speed of the shuttle is smaller than a predetermined minimum and must result in the stoppage of the loom.

FIG. 5 shows the additional elements required for this embodiment which supplement the evaluating device of FIG. 4. The signalling pulses appearing at the input (1) of the evaluating device are examined in a further parallel chain of gates T T The gate T is operated by a time determining device T which determines the length of the time interval T shown in FIG. 3, line (9).

The beginning of T is released simultaneously with the beginning-of Z by the rear edge of the pulse R (point (x) in FIG. 4 and FIG. 5). The end of T defines the beginning of the control interval, so that the smallest permissible average speed of the shuttle is provided at the feeler location by the duration of the intervals R+T in conjunction with the distance of the marking elements M and M in the shuttle. The end of the control interval wherein no signalling pulses should arise, is determined by the end of the condition Z with the aid of gate T Thus the slowest shuttle speed which can be supervised in this manner depends upon the time constant Z. The outer limit for the control interval is provided by the time of the appearance of the next expected signalling impulse in the following phase.

Signalling impulses which appear during the control interval, pass through the gate T which is conductive in the condition T, and through the gate T which is conductive in the condition Z, to the point (y) of the evaluating device and produce a control pulse to stop the loom.

As a rule, the speed of the shuttle at its entry into the shed is somewhat different from its speed when it leaves the shed, so that it may be advisable to change the time constant of the time determining device T with the aid of the time determining device K, depending as to whether the shuttle is in the phases I and III or the phases II and IV. However, the supervision with the aid of K can be limited to phases I and 111, operating with a fixed T.

It is apparent that the described control and evaluating devices have been given solely by way of illustration of the process and apparatus of the present invention and that they are capable of many variations and modifications within the scope of the present invention.

More particularly, the illustrated embodiment of an evaluating device can be adapted to any desired operational program since in principle each function can ae carried out in each phase. Furthermore, the sensing device can operate with other than electro-optical means. for example, partially with inductive signal transmission. The arrangement of impulse producing elements in shuttles can be also adapted in any suitable manner to existing conditions and desired functions.

The process and apparatus of the present invention in each of their applications provide a complete supervision of weft insertion with comparatively simple means. whereby the sensing section of the apparatus as Well as its evaluating section are greatly simplified while their operation remains insensitive to all disturbances.

What is claimed is:

1. A method for supervising weft insertion in a flat loom having a drive and a reciprocating shuttle movable through a shed and carrying a weft bobbin, said method comprising the steps of deriving a sequence of pulses from the shuttle, said sequence including information as to the presence of the weft thread and the broken or unbroken condition thereof and as to the presence of a minimum amount of thread on the weft bobbin, and of assessing said sequence with regard to the occurrence of pulses representing these items of information in order to produce control signals for controlling the operation of the loom, wherein the shuttle has marking elements and wherein said sequence of pulses contains additionally information relating to the shuttle speed, this additional information being evaluated separately on the basis of the time lag between signal pulses derived from said marking elements.

2. An apparatus for supervising weft insertion in a flat loom having a drive and a reciprocating shuttle movable through a shed and carrying a weft bobbin, said apparatus comprising, in combination, a sensing device for deriving a sequence of pulses, said sequence containing at least information as to the presence of and the condition of the weft thread and as to the presence of a minimum amount of thread on a weft bobbin and a discriminating device for assessing the sequence with regard to the occurrence of pulses representing these items of information in order to produce control signals for controlling the operation of the loom, and pulse generating means for generating timing pulses from the loom drive, wherein the timing pulses are fed to the discriminating device in which a signal is then determined depending on whether signal pulses occur within specified intervals of time in specified phases of the operating cycle of the reciprocating shuttle, wherein said discriminating device determines at each passage of the shuttle through a shed, a first interval of time related to the loom drive and by means of signal pulses, the start of further time intervals within and outside the first interval and wherein a signal pulse occurring within a specified period of time related to the loom drive as well as within a specified period of time related to the signal pulse sequence causes a control signal to be released.

3. Apparatus according to claim 2, comprising elements arranged in the shuttle for the purpose of producing the sequence of signal pulses, the operation of said elements being affected by the running weft thread and the amount of thread on the weft bobbin, and elements which are independent of outside influence and cooperate with the sensing device to produce signal pulses at the passage of the shuttle independently of the condition of the weft thread and the Weft bobbin.

4. Apparatus according to claim 2, wherein the discriminating device comprises timing elements which are controlled by the loom and timing elements triggered by signal pulses, and gate circuits which are subject to the influence of the timing elements and determine the path of the signal pulses through the discriminating device.

5. A method in accordance with claim 1, comprising generating timing pulses from the loom drive and deter- 9 mining whether signal pulses occur wihin specified intervals of time in specified phases of the operating cycle of the shuttle.

6. A method in accordance with claim 5, comprising determining by means of pulses at each passage of the shuttle through the shed a first interval of time related to the loom drive and the start of further time intervals within and outside the first interval, and causing a control signal to be released by a signal pulse occurring Within a specified period of time related to the loom drive and 10 Within a specified period of time related to the signal pulse sequence.

7. A method in accordance With claim 5, wherein said determination of the occurrence of signal pulses includes 1-1 a control signal is released when no signal pulse had occurred.

References Cited UNITED STATES PATENTS 3,053,138 9/1962 Loepfe 139273.1 3,181,573 5/1965 Stutz 139341 3,358,717 12/1967 Schooley 139-341 FOREIGN PATENTS 509,288 1/1955 Canada.

HENRY S. IAUDON, Primary Examiner US. Cl. X.R.

determination of an interval of time at the end of Which 15 139341, 371 

